Hi, new here and Ive learned a lot here just reading but now I have a problem that I just can't figure out. I have an issue where the engine will just quit when I use the choke. The bike will run fine cold without it but for some reason the choke doesn't work like it should. I have rebuilt the carb, and I have made sure that the choke adjustment is good. I have another 400 that I rebuilt the carb on and it works like it should, with the choke on, the idle hops up and it richens it.

What seems weird to me is that even without the choke I can start mine and it fires right up no problem, the other 400 you have to use the choke or it will crank all day long and never fire. This tells me that the idle circuit is dumping fuel in excess of what it should, and the fact that the idle air screw doesn't seem to affect it much confirms that.

So what could be clogged or not working for me to see these symptoms?

 

Check jetting differences if any on both machines and float levels.Things like small air leaks at the base gasket,intake manifold or crank seal could cause lean running conditions,lower compression on one machine could cause it to die with the choke fully on where the other one would just have a higher idle. Plus small differences in air screw settings,needle clip position,etc can cause differences. Just depends on what altitude and temp also you're at also. Down here we had to drop the main jet from 200 stock to a 190 or 180 as they ran too rich for most people.